The only other thing I carry that hasn't already been mentioned is a chain tool, short length of chain, and a replacement pin (if Shimano) or Powerlink (if a SRAM chain). Might also carry some duct tape (can wrap just a little around a piece of cardboard)--if a spoke would break, then you can use the tape to hold the loose spoke to another so it doesn't cause further damage (happens more on mtn.bikes than road, but it can happen!)